1. Field of the Invention
The present invention relates to an apparatus for detecting the end of a cloth-overlap.
2. Description of the Background
Conventionally, in a case where an upper cloth is sewn on a lower cloth by a sewing machine, the machine has to be stopped upon detection of the end of a cloth-overlap or a stepped portion formed at a terminus of the upper cloth on the lower cloth. For detecting the end of the cloth-overlap or the stepped portion, a sensor is employed. That is to say, the sensor includes a light emitting portion, a light receiving portion opposing the light emitting portion and a controller which drives the sewing machine. The sensor is provided at an upstream side of a needle and is set on a path along which the cloths are fed by a feed-dog. When the end of the cloth-overlap or the stepped portion is brought into opposition to the light emitting portion during the feeding of both of the cloths, the amount of light is decreased, with the controller then stopping the sewing machine.
However, when both cloths are of thin thickness, a sufficient change in the amount of light sometimes cannot be received by the light receiving portion. Therefore, it is feared that the sewing machine is not stopped despite non-existence of the upper cloth on the lower cloth.